1. Field of the Invention
Embodiments of the present invention generally relate to composite downhole tools for hydrocarbon production and methods for using same. More particularly, embodiments of the present invention relate to a degradable composite tool for isolating one or more hydrocarbon bearing intervals.
2. Description of the Related Art
An oil or gas well is typically a wellbore extending into a well to some depth below the surface. The wellbore may be lined with a tubular or casing to strengthen the walls of the borehole. To further strengthen the walls of the borehole, the annular area formed between the casing and the borehole is typically filled with cement.
After completion of the wellbore, the casing can be perforated to allow hydrocarbon to enter the wellbore and flow toward the surface. Fracturing is a technique used to stimulate production of hydrocarbons from the surrounding formation. Hydrocarbons are often found in multiple zones within a subterranean formation. Such multiple hydrocarbon-bearing zones can require multiple fractures to extract the hydrocarbons.
Current methods for producing hydrocarbons from multiple zones within a formation fracture the lowest zone in the well first, produce the fractured zone, and then isolate the wellbore immediately above the fractured zone so that an adjacent zone can be fractured and produced. Plugs have been used to block off the well bore above each fractured zone to prevent production from flowing down the wellbore to a previously produced zone. After perforating and fracing each individual hydrocarbon bearing zone, the plugs are removed to re-open the wellbore.
The plugs can be removed by drilling. However, a common problem with drilling plugs is that without some sort of locking mechanism, the plug components tend to rotate with the drill bit, which can result in extremely long drill-out times, excessive casing wear, or both. Long drill-out times are highly undesirable, as rig time is typically charged by the hour. Once deactivated, the drilled plug falls to the bottom of the hole. Often, a partially drilled plug falls only part way and can create an obstruction within the wellbore. These obstructions increase the differential pressure through the wellbore, thereby reducing production of the formation.
Furthermore, differential pressure across the plug can be so great that drilling becomes difficult or near impossible. Plugs with built-in check valves have been used to allow one-way flow therethrough, lowering the differential pressure across the plug. However, such valves cannot be used to prevent bi-directional flow through the wellbore. For instance, a plug may be desired to isolate a zone for pressure testing, or for some other temporary isolation need. Once the isolation need is over, re-establishing flow through the wellbore is desired. Such valves with one-way check valves are not suitable for this type of service or workover needs.
There is a need, therefore, for a downhole tool that can temporarily isolate a wellbore and re-establish flow therethrough in-situ.